1. Field of the Invention
The present invention is related to a method of accessing contact features in smartcards, and more particularly, to a method of accessing elementary files associated with contact features in smartcards.
2. Description of the Prior Art
Subscriber identity module (SIM) card is a smartcard that securely stores the international mobile subscriber identity (IMSI) used to identify and authenticate subscribers, short message service (SMS) data and contact information on mobile telephony devices. The hardware structure of a SIM card includes a central process unit (CPU), read-only memory (ROM), random access memory (RAM), electrically erasable programmable read-only memory (EEPROM), and an input/output (I/O) circuit. The hierarchical logic data structure of a SIM card includes 3 types of files: elementary file (EF), dedicated file (DF) and master file (MF).
An elementary file, including a header and a body part, may adopt 3 main types of data structures for storing different types of data: transparent, linear fixed and cyclic. A transparent elementary file defines the data that is managed as a stream of bytes addressed by an offset coming from the start of the file. A linear fixed elementary file or a cyclic elementary file is the data grouped into records, which is a block of bytes with a pre-defined size. Meanwhile, the header of an elementary file marks the overall length and the number of records.
According to the 3rd Generation Partnership Project (3GPP) specification TS 31.102, various types of contact features, such as contact name, primary phone number, secondary phone number, email or contact group, may be stored in a SIM card using different elementary files. In the prior art, a user equipment is configured to access the phone book reference file elementary file EFPBR of its SIM card during the booting procedure, thereby acquiring all contact features supported by the SIM card and accessing the header and body part of all relevant elementary files. However, not all contacts are stored with all types of contact features. Assuming that the SIM card can support 4 types of contact features (contact name, primary phone number, secondary phone number and email) but only the primary phone number is stored for a specific contact, the prior art method still accesses the header and body part of all relevant elementary files associated with contact name, primary phone number, secondary phone number and email. Therefore, the prior art method may lower the booting efficiency.